济阳地区埕岛—垦东构造带中生代的逆冲断层及其与郯庐断裂带的关系

MESOZOIC THRUSTING OF THE CHENGDAO-KENDONG STRUCTURAL BELT AND ITS RELATION TO THE TAN-LU FAULT ZONE IN JIYANG AREA

济阳坳陷埕岛—垦东潜山构造带与郯庐断裂带相邻。4条地震剖面在桩西和埕岛地区中生界内揭示大量逆冲断层,据此分析了该构造带不同部位的沉积—变形特征。郯庐断裂带在中生代不同时期具有不同的活动性质。郯庐断裂带的复杂运动过程是桩西和埕岛地区逆冲断层乃至整个北西向构造带中生代以来构造演化的直接动力之一。埕岛—垦东构造带在中生代之前具有相同的构造演化过程,其后由于郯庐断裂带两侧地块发生复杂的斜向离散—斜向汇聚运动,造成构造带不同位置形成了截然不同的构造面貌,于晚白垩世时形成北西向的埕岛—垦东构造带;新生代时因济阳坳陷形成再次统一接受沉积成为潜山披覆构造带。

The Chengdao-Kendong buried hill belt in the Cenozoic Jiyang Depression was located to the west of the Tan（cheng）-Lu（jiang） fault zone. The belt was once a part of the North China Craton and went through unified evolution process in Paleozoic, and its tectonic development differentiated during Mesozoic. Four seismic profiles revealed that a lot of thrusts occurred in the Mesozoic in Zhuangxi and Chengdao areas. Based on the analyses of the Tan-Lu fault zone＇s movements in Mesozoic, the creation of the buried hill belt was discussed. The Tan-Lu fault zone might be an oblique-convergence and shearing orogenic belt during Juro-Cretaceous. Because of its sinistral shearing along the continental margin in Early-Middle Jurassic, the neighboring Kendong area uplifted in that time. The accelerated shearing and intracontinental orogeny in the latest Middle Jurassic and earliest Late Jurassic resulted in the first generation of thrusting in the belt. The Su-Wan Block collided the Jiao-Liao Craton in Late Jurassic and Early Cretaceous, when the western plate of the Tan-Lu fault might be an obducted one and the Chengdao-Kendong areas extended. The Yanshanides collapsed in the latest Early Cretaceous and Late Cretaceous, the Chengdao-Kendong areas were just situated on the shoulder region so that the second generation of thrusting occurred, which created the Chengdao-Kendong structural belt. With formation of the Jiyang Depression in Cenozoic, the belt depressed and became a buried hill belt and separated the Zhanhua Sag from the Huanghekou Sag.